Door latching mechanisms, especially those used in automobile or other vehicles, typically required latch pins which project from a door post or jamb. These pins are held by a partially revolving clasping mechanism in a manner well known in this art. For the sake of easy operation, the clasping mechanism is easily and automatically rotated about the latch pin when the door is closed. This arrangement is very successful for normal opening and closing of the automobile doors. However, the relative positioning of the latch pin and the clasping mechanism is critical for the proper operation of such a system. Consequently, this arrangement becomes very unreliable when the vehicle is subjected to an impact that may force the door and the door jamb out of alignment. It is often quite common for doors to spring open when the vehicle is subject to impact because such impact often forcibly misaligns the door and the door jamb, or deforms the door causing the clasping mechanism to partially rotate and separate from the latch pin.
Also, conventional latch pins normally pick up grease or other lubricants used with the door clasping mechanism. Such lubricants can be transferred to the clothing or skin of occupants when entering or exiting the vehicle. Also, under some circumstances, the clasping mechanism, as well as the exposed latch pins, can become hazardous to the passengers. Further, the latch pins and the clasping mechanism, as well as the exterior handles used to operate them, are often considered unsightly and thus, not well suited for vehicles being displayed in shows.
Many of the aforementioned characteristics can lead to hazardous conditions. Some remain despite the many efforts made in the conventional art to correct these deficiencies.
Many of these drawbacks have been addressed in related patent application Ser. No. 08/908,254. However, in many security door arrangements, especially those in armored vehicles, extremely simple and durable mechanisms are a necessity. In particular, the use of electrical door switches, which can be deteriorated by hard or constant use, is not suitable for all applications requiring a security door latch mechanism. Also, in many security door applications, there is need for a secondary or auxiliary latching mechanism that is extremely reliable, and latches under all conditions, eventhough the primary latching system may not engage.